Treatment of unruptured intracranial aneurysms using internally expanding coils

The International Subarachnoid Aneurysm Trial (ISAT) showed that patients with intracranial aneurysms treated with coil embolization have better clinical outcomes than those undergoing neurosurgical clipping. However some patients treated endovascularly have recurrence of aneurysms. Low packing density is often cited as a reason for recurrence. Coiling with hydrogel covered coils significantly improves the packing density. We report our initial experience in using a newly introduced design of hydrogel coils.

Three consecutive patients with unruptured aneurysms were treated with hydrogel coated coils. During embolization, a stable framework was first established with bare metal coils, and gel coated coils were used subsequently to increase the packing density. After the procedure, packing density was estimated by calculating the compaction ratio using an online calculator.

Successful coil embolization was achieved in all 3 patients. Hydrogel coated coils comprised 11, 63 and 72% of the total coils deployed. One patient had coil herniation that required stent deployment. All patients remained neurologically intact during and after the procedure. Follow-up angiography in 2 patients at 6 months revealed aneurysm stability without any residual neck remnant.

The softness of the hydrogel allowed us to deploy coated coils with good packing density. A slight expansion of these coils at the neck can be expected to reduce any neck remnant and potentially inhibit recurrence.